Balanced slide valves



Jan. 13, 1970 RC. E-ELES I' 3,489,17

BALANCED SLIDE VALVES Filed Feb. 19, 1968 6 Sheets-Sheet 1 INVENTOR Raefl e/a; A fir 7 mm ma. SMMM, u m -mm ATTORNEY Jan. 13, 1970 R. C.EELES ETAL 3,489,173

BALANCED SLIDE VALVES Filed Feb. 19, 1968 6 Sheets-Sheet 2 ATTORNEY R. c. EELES ETAL BALANCED SLIDE VALVES 6 Sheets-Sheet 5 WFWW Z 3 B Jan. 13; 1970 Filed Feb. 19, 1968 Jan. 13, 1970 R. c. EELES ETA!- 3, 8

BALANCED SLIDE VALVES Filed Feb. 19, 1968 6 Sheets-Sheet 4 \r (O (D 9 o) Ev INVENTOR F iled Feb. 19, 1968 Jan. 13, 1970 c, EELES 'ETA'L 3,489,173

BALANCED SLIDE VALVES 6 Sheets-Sheet 5 INVENTOR fiaber+@. Ee/af Jan. 13, 1970 Filed Feb. 19, 1968 R. C. EELES ETAL BALANCED SLIDE VALVES 6 Sheets-Sheet 6 BY PKG Uh 7T? ATTGRNEY United States Patent $489,173 BALANCED SLIDE VALVES Robert C. Eeles, Leckhampton, Cheltenham, and Victor R. Slimm, Winchcombe, Cheltenham, England, assignors to Dowty Technical Development Limited, Cheltenham, England, a British company Filed Feb. 19, 1968, Ser. No. 706,457 Claims priority, application Great Britain, Feb. 21, 1967, 8,295/ 67 Int. Cl. F161: 31/44 US. Cl. 137-596 Claims ABSTRACT OF THE DISCLOSURE In a slide valve unit having a single inlet connection and a single exhaust connection wherein unloader porting is provided in the respective sliders such that when the sliders are all in their neutral positions a direct unloader route is provided from the single inlet connection to the single exhaust connection, the opposite side surfac"s of each slider adjacent the porting are provided with balance recesses of such shape and dimension, so positioned with respect to the respective unloader port and so interconnected across the respective slider by flow-restrictive passage means that, irrespective of the operational position" of the slider, they afford substantially complete hydrostatic balance of the slider.

FIELD OF THE INVENTION This invention relates to slide valves.

SUMMARY OF THE INVENTION According to this invention a slide valve includes a casing housing at least one slider, the or each slider being provided with means for directing pressure fluid, supplied to it, to a respective service controllable thereby, and the or each slider having opposite surf-aces arranged in slidable relation with respect to complementary adjacent sur faces formed in the casing, an unloader port being provided in the or each slider such that when all the sliders are in their neutral positions, the unloader port or ports align with casing ports to provide an unloader route direct from a single inlet connection for the valve to a single exhaust connection for the valve, said opposite surfaces of the or each slider being provided with balance recesses of such shape and dimension, so positioned with respect to the respective unloader port and so interconnected across the respective slider by flow-restrictive passage means that, irrespective of the operational position of the slider, they afford substantially complete hydrostatic balance of the slider.

Grooving may be provided in one of said surfaces running parallel to the plane of movement of the respective slider, so disposed upon that surface and so leading from therespective unloader port, as with the unloader port, to form said flow-restrictive passage means.

The said surfaces and the said complementary adjacent surfaces are preferably flat.

The or each slider may be of linear type in which case it may be of rectangular cross-section.

The balance recesses may be of rectangular shape and may comprise two recesses, one formed on each side, in the direction of slider movement, of'the unloader port in that surface of the slider remote from said single inlet connection, and also one single recess formed in the opposite surface of the slider, said unloader port being so ,cut in the respective slider that it opens from said single recess and passes through the thickness of the slider to the opposite side thereof.

Whether the or any one or more of the sliders are in their neutral positions, or whether the or any or more of the sliders are in a position in which the associated service is operating, the arrangement of balance recesses and restrlctive passageways is such that substantial slider hydrostatic balance is maintained.

Preferably, the effective pressure area for such hydrostatic balance of the slider on the surface of the or each slider remote from the single exhaust connection is less than the effective pressure area on the opposite surface thereof, thus to produce a substantially constant clearance between the respective slider and the adjacent casing surfaces for substantially complete balanced fluid support of the slider, said clearance being substantially equal on both sides of the slider. The arrangement is also such that large leakage losses to exhaust are avoided and also when all the sliders are in their neutral positions, the pressure drop across the slide valve from the inlet connection to the exhaust connection is kept relatively very low.

One at least of the sliders may be so constructed as to have the facility for float of a service which it controls.

The said grooving may comprise four channels of V- shaped cross-section.

Filter recesses may be provided in each slider to place said grooving in communication with the respective unloader port, the depth of said filter recesses being less than that of said grooving.

Inching slots may be provided at the operative edges of each unloader port in that'surface of the respective slider remote from the inlet connection.

BRIEF DESCRIPTION OF THE DRAWINGS Of the seven accompanying drawings,

FIGURE 1 is an end elevation of a banked slide valve unit having four sliders,

FIGURE 2 is a part cross-sectional side elevation of the unit shown in FIGURE 1,

FIGURE 3 is a cross-sectional taken along the line IIIIII on FIGURE 2,

FIGURE 4 is an enlarged view of a slider of the banked slide valve unit when viewed in the direction of the arrow IV upon FIGURE 2,

FIGURE 5 is a cross-section taken along the line V-V on FIGURE 2,

FIGURE 6 is a partial plan view of the slide valve unit shown in FIGURES 1 to 5, and,

FIGURE 7 is a cross-section taken along the line VIIVII on FIGURE 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, a banked multiple slide valve unit 11 comprises five casing plates 12, 13, 14, 15 and 16 interspaced one from another by four slider frames 17, 18, 19 and 20, each of which incorporates a chamber 21 of such shape as to provide a linear slide for a ported slider. The four sliders are shown at 22, 23, 24 and 25 in FIGURES 2 and 5, and these are identically-shaped in front elevation, such shape being shown in FIGURES 3 and 4.

The casing plates and slider frames are held together in banked unit assembly by means of through rods, at

26 and 27 in FIGURE 7, to which retaining nuts as at 28,

this control rod passing through a bearing 40 into the respective chamber 21 and its inner end portion being connected by way of a tongue-and-slot connection at 41 to the left-hand end portion of the respective slider 23 as shown in FIGURE 3. A similar tongue-and-slot connection 42 is provided at the other end portion of the slider to a rod 43 which is slidable in a bearing 44, both the bearings 40 and 44 being provided in the respective slider frame.

The spring-box is of conventional form and ensures that one manual pressure is relieved from the control lever 34 the respective slider is automatically returned to its neutral position, that is the position in which the slider 23 is shown in FIGURE 3.

The casing plate 12 at one end of the banked unit 11 is provided with a single inlet connection 45 common to the whole bank, while the casing plate 16 at the opposite end of the unit is provided with a reservoir connection 46, also common to the whole bank.

Aligned ports 47, 48, 49, 50 and 51 are respectively provided in the casing plates 12, 13, 14, and 16, and also at 52, 53, 54, 55 respectively in the slider frames 17, 18, 19 and 20. These aligned ports form a pressure liquid supply passage generally indicated by the reference numeral 56 which runs the length of the bank and is in open communication with the inlet connection 45. This passage is also in communication with the reservoir connection 46 through a suitable relief valve 57 incorporated in the reservoir connection casing plate 16.

As shown in FIGURE 2, a branch passage 58 is taken from the inlet connection 45 in the casing plate 12 and leads to elongated main porting 59 cut through the slider 22. Whatever the position of the slider 22, the passageway 58 is always in communication with this porting a check valve 60 being provided in the passageway to permit flow of liquid only in a direction towards the slider 22.

Similarly, a branch passageway 61 is taken from the passage 56 and leads through another check valve 62 to elongated main porting 63 cut through the slider 23. Similar branch passageways and check valves are provided in association with the remaining and similar two sliders 24, 25 in the banked unit.

The end portions 64 and 65 of each of the chambers 21 in which the respective sliders are slidingly mounted are all intercommunicated by suitable porting and ducting and are together all in communication, as shown in FIG- URE 5, with a cross-cavity 66 formed in the casing plate 16, this cavity being directly open to the outlet connection 46. As will be seen from the dotted detail in FIGURE 1, a cross-duct 67 is in communication with cavities 68 and 69 formed at either side of the inlet connection casing plate 12, so that at no time during the operation of any one or more of the sliders of the unit can there be any trapped liquid which might cause undesirable functioning of the unit.

Each casing plate 12, 13, 14 and 15 on that side of the respective slider 22, 23, 24 and 25 remote from the outlet connection 46 is provided with a pair of service connections 70, 71; 72, 73; 74, 75; 76, 77; each pair of service connections connecting with a respective doubleacting telescopic jack, such as that is shown at S in FIGURE 3 in association with the service connections 72 and 73. Such connection with the jack is through pipes 78 and 79.

As shown in FIGURE 7 service ports are arranged in pairs as at 80, 81; 82, 83 in the faces of the casing plates adjacent each respective slider. These ports open into pairs of ducts 84, 85; 86, 87 in respective adjacent casing plates. Each pair of ducts 84, 85; 86, 87 communicate with respective ports 88 and 89 in the respective slider frame as shown in FIGURE 3, and thus communicate with each other. The respective pair of ducts and associated port 88 or 89, are also in communication through ducting 90 and 91, respectively shown in dotted detail in FIGURE 3, with the respective service connection 72, 73.

Associated with each service connection is a service line relief valve, those associated with the connections 72 and 73 being shown at 92 and 93 in FIGURE 3. These relief valves each comprise a spring-loaded valve member 94 which is stepped in diameter and whose smaller end face area 95 is subjected to the pressure pertaining in the service line connection. The valve member is displaceable against spring pressure on the attainment of a predetermined maximum pressure in the service line port, to relieve this pressure to drain through a passageway 96 which leads to the chamber 64 or 65, as shown in FIGURE 3, and thus to reservoir.

The pairs of service ports 80, 81; 82, 83 are so positioned in relation to the respective slider 22, 23, 24 and 25 that when the slider is in its neutral position as shown in the case of the slider 25 in FIGURE 7, seal-housing ports 97, 98 cut in the slider are in alignment with the service ports. As shown in FIGURE 3, these seal-housing ports are provided in the same plane as the elongated main porting 63.

The seal-housing ports 97 and 98 of each slider include sealing means in the form of tubular members 99 and 100 which are urged into sealing engagement with the adjacent casing plate faces by a common sealing ring 101. Such a seal construction is disclosed in the specification of co-pending US. Patent 3,370,611.

From the arrangement of service ports and ducting it will be seen that flow of liquid towards the slider and away from the slider occurs along a bifurcated flow path.

The two end edges 102 and 103 of each slider are respectively co-operable with the two pairs of service ports 80, 81; 82, 83, so that when the respective slider is moved away from its neutral position, for example as shown in FIGURE 7 at 24, for pressurising one pair of service ports, (in this case the pair 82, 83) one side of the associated double-acting jack S. controllable thereby, is pressurised. Simultaneously, the other pair of service ports 80, 81 are opened by the respective end edge 102 of that slider so that the other side of the jack is placed in communication with reservoir through the pipe 78, service connection 72 and chamber 64.

Each slider 22, 23, 24, 25 is provided with an unloader port 104 of rectangular shape as shown in FIGURE 3, cut completely through the thickness of the slider and disposed in a plane parallel with but displaced from and beneath the plane containing the main and seal-housing porting 63, 97, 98. In that face 105 of each slider remote from the reservoir connection 46 there is provided an elongated rectangular balance recess 106, the unloader port 104 opening from this recess.

In that face 107 of the slider remote from the inlet connection 45, and as shown in FIGURE 4, two further balance recesses 108 and 109 are provided, these being also of rectangular shape as shown, and spaced from, in the direction of the slider motion, and on either side of, the unloader port 104.

As also shown in FIGURE 4, the slider is provided with shallow steps 110 and 111 at both end portions and on both sides of the respective slider, the stepped portions being parallel with the straight end edges of the slider in the plane of the unloader porting, and since the end edges are both subjected to drain conditions, these portions are also.

On the face 107 of each slider there is provided grooving which runs parallel to the plane of movement of the slider. This grooving comprises four channels 112, 113, 114, 115 of V-shaped cross-section so disposed that they lead from part-circular filter recesses 116 and 117 into the balance recesses 108 and 109 respectively, the filter recesses 116 and 117 themselves opening directly into the unloader port 104. The filter recesses 116 and 117 are very shallow, their depth into the face 107 being in this embodiment .0025 inch. The V-shaped channels 112, 113, 114, 115 are each .015 inch wide and .007 inch deep, The balance recesses 108 and 109 are .030 inch deep.

Thus the unloader port 104, the filter recesses 116 and 117, and the channels 112, 113, 114, 115 together form respective passageways which lead from the single balance recess 106 in the face 105 on the inlet side of the respective slider to the two balance recesses 108 and 109 in the face 107 on the outlet side of that slider.

Substantially semi-circular shaped inching slots 118 and 119 are provided at the operative edges of the unloader port 104 on the face 107 of the slider.

As will be understood from FIGURES 2 and 5, when all the sliders 22, 23, 24 and 25 are in their neutral positions, the respective telescopic jacks will be static and the unloader ports 104 of the respective sliders will be in alignment with associated casing ports 120, 121, 122, 123 and 124 respectively formed in the casing plates 12, 13, 14, 15 and 16, thus to provide an unloading route 125 direct from the single inlet connection 45 to the single reservoir connection 46, this route by-passing the through passageway 56 and its relief valve 57.

With all the sliders 22, 23, 24 and 25 in their neutral positions, the liquid supply at pressure P available in each single balance recess 106 in the face 105 of each slider passes through the respective unloader port 104, the filter recesses 116 and 117 in the face 107 of the respective slider and through the two pairs of restrictive V- shaped channels 112, 113, 114, 115 respectively to the balance recesses 108 and 109. These restrictive channels create a pressure drop across the respective slider so that the pressure in both of said two balance recesses 108 and 109 is substantially /2P.

Thus the pressure gradient across the face 107 of the slider from the unloader port 104 in both directions of linear movement falls from P at the unloader port to substantially X21 at the respective balance recesses 108 and 109, and to drain value at the respective stepped portion 110, 111 at the respective end edge of the slider.

On the face 105 of the respective slider the pressure from the unloader port 104 in both directions of linear movement falls from P at the respective edge of the single balance recess 106 to drain value at the edge of the respective stepped portion 110, 111 at the respective end edge of the slider.

The effective pressure area on the face 105 of each slider is less than the total effective area on the face 107. The pressure distribution over both faces 105 and 107 is such that the clearance between the slider and the casing components on both sides thereof is maintained substan tially equal, of the order of .0005 inch. Further, the balancing system is automatically self-restoring to the equilibrium condition in which the centre of pressure is maintained in the necessary position for balance.

Also, the V-shaped cross-section channels 112, 113, 114, 115, in the face 107 of each slider, themselves afford an additional hydrostatically balancing and restoring effect about the longitudinal axis of the slider.

Each slider is thus floating in a substantially fully hydrostatically-balanced condition when in its neutral position. The filter recesses 116 and 117 are more shallow than the channels 112, 113, 114, 115 to prevent any foreign particles in the pressure supply, and which pass through the unloader port 104, from gaining access to the channels Where they might otherwise cause binding of the slider between the adjacent casing plates.

Considering one particular slider in the bank, for example the second slider 23 as viewed in FIGURES 2 and 5, if another slider, for example the slider 24 downstream thereof, in the unloading sense, is moved to the position shown in FIGURE .5 to select the operation of its associated service While the slider 23 is maintained in its neutral position, the direct unloader route from the inlet connection 45 to the reservoir connection 46 is closed by the movement of the selected slider.

The pressure fluid available at the inlet connection 45 is then re-directed to the service through the associated check valve, slider 24 and ducting and the pressure in the unloader passageway upstream of the slider 24 rises. Full pressure P is applied to both sides of the slider 23, the

6 balance recesses 106, 108, 109 thereof, their effective disposition, and the restrictive channels 112, 113, 114, 115 again being such with pressure at /2P in the balance recesses 108 and 109, as to maintain the slider 23 in the substantially balanced state.

The slider 25 downstream of the selected slider 24 (in the unloading sense) is however now subjected to reservoir pressure on both faces and 107 thereof, but nevertheless is in substantial hydrostatic balance.

Considering now the case of the slider 24 which has been moved away from its neutral position downwardly in FIGURE 5 to one of its two service-selecting positions, the respective elongated main porting 63 is positioned so that it directs pressure fluid to its service connection 75, while the other service connection 74 is open, by the appropriate straight end edge portion of that slider, to reservoir.

With the slider 24 in this position, its unloader port 104 is blanked off by the adjacent casing plate 15 with which the face 107 co-operates, but the single recess 106, although displaced with respect to the unloader port 122 in the casing plate 14, is still in communication with that port.

Hence, pressure liquid can still pass from the port 122 into the respective single balance recess of the slider 24 through the unloader port 104 and the respective filter recesses 116 and 117 and through the V-shaped channels 112, 113, 114, on the face 107 to the two balance recesses 108, 109 of that slider. However, although the pressure distribution is the same as before over the face 105 of the slider, it is not the same over the face 107 because a portion of that face between the unloader port 104 and the balance recess 109 is subjected to drain conditions since the blanked-01f unloader port 123 in the downstream adjacent casing plate 15 is superimposed upon it.

Thus, the pressure distribution towards that end of the slider and on the face 107 starts at P and since the lapover of the unloader port 123 and slider is only small at this portion, falls sharply to drain value. Likewise, the pressure in the balance recess 109 falls sharply off to drain value on both sides of this balance recess, because on one side limited leakage occurs almost directly to drain through the casing unloader port 123, and on the other side limited leakage occurs almost directly to drain at that end, the upper end in FIGURE 5, of the slider. However, despite such limited leakage, a positive land effect is now provided for substantial sealing at the edges of this balance recess 109 to an extent which ensures that a pressure can now be maintained in this recess. This pressure is caused by the clearances, overlaps and flow conditions to be in excess of its original value, as in neutral, and in excess also of the pressure which under these conditions is now effective in the balance recess 108. Such higher pressure in one balance recess and lower pressure in the other balance recess affords a new condition of balance about the centre of the slider in this new, selected, position of the slider.

e new pressure distribution is therefore such that again substantially complete hydrostatic balance of the slider is afforded, and the arrangement of balance recesses and restrictive passageways ensures that the condition of hydrostatic balance is maintained by the restoring characteristics inherently produced by the arrangement, despite fluctuations in the value of P.

This is also the case when the slider is in its other selected position, the portion of the face 107 between the unloader port 104 and the balance recess 108 instead having the blanked-01f unloader port 123 superimposed upon it.

Considering now the case where the said slider 24 has been selected, and now a second slider, for example the slider 23 which is closer to the inlet connection 45 is now also selected, so that the two associated services are simultaneously operated, full pressure P is applied to both faces 7 105 and 107 of the slider 23 because there is no direct unloader connection to reservoir.

However, in either one or other of the selected positions of the slider 23, the two balance recesses 108, 109 thereof in the face 107 are so positioned in relation to the unloader port 122 in the adjacent casing plate 14 that a new pressure distribution across that face occurs to give apropriate adjustment in slider centre of pressure. Thus, the effective fluid-pressure-loading areas and the pressure distribution upon the slider 23 are such that substantial hydrostatic balance is maintained.

The arrangement of hydrostatically-balanced sliders above-described ensures that when the unloader route 125 is open, the pressure drop from the inlet connection 45 to the reservoir connection 46 is maintained as low as possible. Further, the arrangement ensures that a relatively small slider movement is required for service selection, and since the sliders are floating on a cushion of hydraulic liquid, the manual operating loads required are relatively small.

In addition, the arrangement is such that substantial hydrostatic balance is maintained in the transition between neutral and the operative states referred to.

The invention is in no way limited-to the precise form of recesses or the precise arrangement of restrictive channels, as variations on the arrangement above-described can be made, again with the object of providing substantially hydrostatically-balanced sliders.

Although in the above-described embodiment the services referred to are of double-acting type, in alternative embodiments of the invention one or more sliders in a bank may be arranged and ported in a manner whereby they are each suitable for controlling a single-acting service.

Further, in other alternative embodiments one or more sliders may be arranged and ported whereby they are suitable for controlling rotary motors and like devices.

The invention is in no way limited to the provision of sliders wholly of rectangular cross-section.

Further, the invention is in no way limited to th balance recesses being formed in fiat surfaces, as in other embodiments such balance recesses may be formed in surfaces of other shape, these surfaces co-operating with casing surfaces of parallel and complementary shape.

Again, the invention may be applied in the control of services required to have the facility for float, in the manner described in US. Patent 3,367,243.

The invention is in no way limited to banked slide valve units, as it may equally well be applied to slide valve units having only one slider for control of a single associated service.

What we claim is:

1. In a slide valve including a casing, having a single inlet connection and a single exhaust connection, said casing housing at least one slider, each of which is provided with means for directing pressure fluid supplied to it to a respective service controllable thereby, and each of which has opposite surfaces arranged in slidable relation with respect to complementary adjacent surfaces formed in the casing, and an unloader port being provided in each slider such that when all the sliders are in their neutral positions, each unloader port aligns with casing ports thus to provide an unloader route direct from the single inlet connection to the single exhaust connection, the improvement comprising flow restrictive passage means in each slider, and recess means disposed in the aforesaid opposite surfaces of the slider, and interconnected by the passage means, so that the slider assumes a state of substantial hydrostatic balance adjacent the port, irrespective of the operational position thereof.

2. A slide valve is claimed in claim 1, wherein grooving is provided in one of said surfaces running parallel to the plane of movement of the respective slider, so disposed upon the surface and so leading. from the respective unloader port, as with the unloader port, to form said flow-restrictive passage means.

3. A slide valve as claimed in claim 2, wherein said grooving comprises four channels of V-shaped cross-section.

4. A slide valve as claimed in claim 2, wherein filter recesses are provided in each slider to place said grooving in communication with the respective unloader port, the depth of said filter recesses being less than that of said grooving.

5. A slide valve as claimed in claim 1, wherein said surfaces and said complementary adjacent surfaces are flat.

6. A slide valve as claimed in claim 1, wherein each slider is of linear type and of rectangular cross-section.

7. A slide valve as claimed in claim 1, wherein the balance recesses are of rectangular shape and comprise two recesses, one formed on each side, in the direction of slider movement, of the unloader port in that surface of the slider remote from said single inlet connection, and also one single recess formed in the opposite surface of the slider, said unloader port being so cut in the respective slider that it opens from said single recess, and passes through the thickness of the slider to the opposite side thereof.

8. A slide valve as claimed in claim 1, wherein the elfective pressure area for hydrostatic balance of the slider on the surface of each slider remote from the single exhaust connection is less than the effective pressure area on the opposite surface thereof, thus to produce a substantially constant clearance between the respective slider and the adjacent casing surfaces for substantially complete balanced fluid support of the slider, said clearance being substantially equal on both sides of the slider.

9. A slide valve as claimed in claim 1, wherein inching slots are provided at the operative edges of each unloader port in that surface of the respective slider remote from the inlet connection.

10. A slide valve as claimed in claim 1, wherein said means for directing pressure fluid to a respective service includes elongated main porting provided in each slider which in all positions of the respective slider is open to ducting capable of receiving pressure liquid direct from said inlet connection through a respective check valve, said porting when the respective slider is moved in either direction away from its neutral position communicating with porting which is connectible to said service.

References Cited UNITED STATES PATENTS 3,371,682 3/1968 Flint 251-282 XR 3,387,628 6/1968 Flint et a1 137596.12 2,827,924 3/1958 Towler et al 251-283 XR FOREIGN PATENTS 402,502 12/ 1933 Great Britain.

HENRY T. KLINKSIEK, Primary Examiner US, Cl. X-R. 251282 

